attribute vec3 a_CubeVertexPos;
uniform mat4 u_CubeMVPMatrix;
varying vec3 v_pos;

void main(void)
{
	vec4 positionL = vec4(a_CubeVertexPos, 1.0);
    gl_Position = u_CubeMVPMatrix * positionL;
    //gl_Position.w = gl_Position.z * 1.001; // (z / w) < 1
    v_pos = a_CubeVertexPos;
    v_pos.z = -v_pos.z;
}